Composition and process for controlled radical polymerization using multifunctional initiator/regulator compounds

ABSTRACT

The present invention relates to a polymerizable composition comprising a) at least one ethylenically unsaturated monomer and b1) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl and a free radical initiator or b2) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ether. Further aspects of the present invention are a process for polymerizing ethylenically unsaturated monomers, the (co)polymers obtainable by this process and the use of multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyls in combination with a free radical initiator, or a multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ethers for controlled polymerization. In a particularly preferred embodiment at least one additional heating step at a temperature from 140 to 280° C. is applied after polymerization is completed.

This application claims the benefit of Ser. No. 60/113,238, filed Dec. 21, 1998.

The present invention relates to a polymerizable composition comprising a) at least one ethylenically unsaturated monomer and b1) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl and a free radical initiator or b2) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ether. Further aspects of the present invention are a process for polymerizing ethylenically unsaturated monomers, the (co)polymers obtainable by this process and the use of multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyls in combination with a free radical initiator, or a multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ethers for controlled polymerization.

In particular, this invention relates to stable free radical-mediated polymerization processes which provide homopolymers, random copolymers, block copolymers, multiblock copolymers, graft copolymers and the like, at enhanced rates of polymerization and enhanced monomer to polymer conversions.

U.S. Pat. No. 4,581,429 to Solomon et al., issued Apr. 8, 1986, discloses a free radical polymerization process which controls the growth of polymer chains to produce short chain or oligomeric homopolymers and copolymers, including block and graft copolymers. The process employs an initiator having the formula (in part) R′R″N—O—X, where X is a free radical species capable of polymerizing unsaturated monomers. The reactions typically have low conversion rates. Specifically mentioned radical R′R″N—O·groups are derived from 1,1,3,3 tetraethylisoindoline, 1,1,3,3 tetrapropylisoindoline, 2,2,6,6 tetramethylpiperidine, 2,2,5,5 tetramethylpyrrolidine or di-t-butylamine. However, the suggested compounds do not fulfill all requirements. Particularly the polymerization of acrylates does not proceed fast enough and/or the monomer to polymer conversion is not as high as desired.

EP-A-735 052 discloses a method for preparing thermoplastic polymers of narrow polydispersities by free radical-inibated polymerization, which comprises adding a free radical initiator and a stable free radical agent to the monomer compound. However the compounds specifically disclosed therein do not fully satisfy the need of high conversion rates, which is a prerequisite for industrial scale up.

JP 08-269117 published 31.3.1995 describes the polymerization of vinyl monomers with nitroxides such as the nitroxides of bis(2,2,6,6-tetramethyl-4-piperidyl)sebaic acid ester and tetrakis(2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4 butanetetracarboxylate.

It remains however still a problem to achieve a high conversion in short time at a low polydispersity.

The compounds of the present invention provide polymeric resin products having low polydispersity, particularly when the polymer is heated for a certain time after polymerization is completed. In addition the monomer to polymer conversion proceeds in a short time. Thus making the compounds particularly suitable for industrial polymerization processes.

One subject of the invention is a polymerizable composition, comprising

a) at least one ethylenically unsaturated monomer or oligomer, and

b) a compound of formula (I)

 in which n is the number 1 or 2, and R₁ is a group of the formula

 in which

G₁ and G₂ are hydrogen, methyl or, together, are a substituent ═O,

E is —O— or —ND₃—,

A is C₂-C₆alkylene or —(CH₂)₃—O— and

x₁ is the number 0 or 1,

D₃ is hydrogen, C₁-C₁₂alkyl, C₂-C₅hydroxyalkyl or C₅-C₇cycloalkyl,

R₂ is identical to R₁ or is one of the groups —N(G₂₁)(G₂₂), —OG₂₃, —N(H)(CH₂OG₂₃) or —N(CH₂OG₂₃)₂,

R₃, if n=1, is identical to R₁ and,

if n=2, is an —E—D₄—E— group, in which D₄ is

C₂-C₈alkylene or C₂-C₈alkylene which is interrupted by 1 or 2 —NG₂₁— groups,

G₂₁ is C₁-C₁₂alkyl, cyclohexyl, benzyl or C₁-C₄-hydroxyalkyl or a group of the formula

G₂₂ is C₁-C₁₂alkyl, cyclohexyl, benzyl or C₁-C₄hydroxyalkyl, and

G₂₃ is hydrogen, C₁-C₁₂alkyl or phenyl, or

G₂₁ and G₂₂ together are C₄-C₅alkylene or C₄-C₅oxaalkylene, for example —CH₂CH₂—O—

CH₂CH₂—, or a group of the formula —CH₂CH₂—N(G₁₁)—CH₂CH₂—; and

G₁₁ is O· or —O—X, wherein

X represents a group such that the free radical X· derived from X is capable of initiating polymerization of ethylenically unsaturated monomers; and

if G₁₁ is O·, a source of free radicals is additionally present.

Some examples of the several variables in the formula (I) are given below.

Any C₁-C₁₂alkyl substituents are, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tertbutyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl or n-dodecyl.

Any hydroxyalkyl substituents are, for example, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.

Any C₅-C₇cycloalkyl substituents are, for example, cyclopentyl, cyclohexyl or cycloheptyl. Cyclohexyl is preferred.

C₂-C₆alkylene A is, for example, ethylene, propylene, 2,2-dimethylpropylene, tetramethylene or hexamethylene.

If G₂₁ and G₂₂ together are C₄-C₅alkylene or oxaalkylene, they are, for example, tetramethylene, pentamethylene or 3-oxapentamethylene.

Preferably n is 1 in formula (I).

Particularly preferred compounds of formula (I) are, wherein n is 1, R₁ and R₃ are a group

and R₂ is identical to R₁ and R₃ or is a group —N(G₂₁)(G₂₂) and the other substituents are as defined above.

Most preferred compounds of formula (I) are, wherein n is 1;

R₁ and R₃ are a group of formula

R₂ is identical to R₁ and R₃, or is a group —N(G₂₁)(G₂₂),

wherein x₁ is 0; G₁ is hydrogen; G₁₁ is O·; E is —ND₃; D₃ is C₁-C₁₂alkyl and G₂₁ and G₂₂ are independently C₁-C₁₂alkyl.

Preferably X is selected from the group consisting of —CH(aryl)₂, —CH₂-aryl,

—CH₂—CH₂—aryl,

(C₅-C₆cycloalkyl)₂CCN, CH₂CH═CH₂, (C₁-C₁₂)alkyl-CR₃₀—C(O)—(C₁-C₁₂)alkyl, (C₁-C₁₂)alkyl-CR₃₀—C(O)—(C₆-C₁₀)aryl, (C₁-C₁₂)alkyl-CR₃₀—C(O)—(C₁-C₁₂)alkoxy, (C₁-C₁₂)alkyl-CR₃₀—C(O)-phenoxy, (C₁-C₁₂)alkyl-CR₃₀—C(O)—N-di(C₁-C₁₂)alkyl, (C₁-C₁₂)alkyl-CR₃₀—CO—NH(C₁-C₁₂)alkyl, (C₁-C₁₂)alkyl-CR₃₀—CO—NH₂, —CH₂CH═CH—CH₃, —CH₂—C(CH₃)═CH₂, —CH₂—CH═CH-phenyl,

—O—C(O)—C₁-C₁₂alkyl, —O—C(O)—(C₆-C₁₀)aryl,

(C₁-C₁₂)alkyl-CR₃₀—CN,

 wherein

R₃₀ is hydrogen or C₁-C₁₂alkyl;

the aryl groups are unsubstituted or substituted with C₁-C₁₂alkyl, halogen, C₁-C₁₂alkoxy, C₁-C₁₂alkylcarbonyl, glycidyloxy, OH, —COOH or —COOC₁-C₁₂alkyl.

Aryl is phenyl or naphthyl.

More preferably X is selected from the group consisting of —CH₂-phenyl, CH₃CH-phenyl, (CH₃)₂C-phenyl, (CH₃)₂CCN, —H₂CH═CH₂, and CH₃CH═CH═CH₂.

Most preferred is a compound of formula (1), wherein G₁₁ is —O·.

Examples of groups of polyalkylpiperidine compounds according to formula (I) are the compounds of the following formulae:

where R′ has the same meaning as in compound 76.

In the above formulae G₁₁ represents —O·, or —O—X, wherein X is as defined above.

Preferably the compound of formula (I) is present in an amount of from 0.01 mol-% to 30 mol-%, based on the monomer or monomer mixture, more preferably in an amount of from 0.05 mol-% to 20 mol-%, and most preferably in an amount of from 0.1 mol-% to 10 mol-% based on the monomer or monomer mixture.

The compounds according to formula (I) are in principal known and may be prepared according to standard procedures as for example described in U.S. Pat. No. 5,216,156, U.S. Pat. Nos. 5,004,770 or 5,204,473.

Preferably the source of a free radical initiator is a bis-azo compound, a peroxide or a hydroperoxide.

More preferably, the source of free radicals is 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methyl-butyronitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1′-azobis(1-cyclohexanecarbonitrile), 2,2′-azobis(isobutyramide)dihydrate, 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, dimethy-2,2′-azobisisobutyrate, 2-(carbamoylazo)isobutyronitrile, 2,2′-azobis(2,4,4-trimethylpentane), 2,2′-azobis(2-methylpropane), 2,2′-azobis(N,N′-dimethyleneisobutyramidine), free base or hydrochloride, 2,2′-azobis(2-amidinopropane), free base or hydrochloride, 2,2′-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide} or 2,2′-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide.

Preferred peroxides and hydroperoxides are acetyl cyclohexane sulphonyl peroxide, diisopropyl peroxy dicarbonate, t-amyl perneodecanoate, t-butyl perneodecanoate, t-butyl perpivalate, t-amylperpivalate, bis(2,4-dichlorobenzoyl)peroxide, diisononanoyl peroxide, didecanoyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, bis(2-methylbenzoyl)peroxide, disuccinic acid peroxide, diacetyl peroxide, dibenzoyl peroxide, t-butyl per 2-ethylhexanoate, bis-(4-chlorobenzoyl)-peroxide, t-butyl perisobutyrate, t-butyl permaleinate, 1,1-bis(t-butylperoxy)3,5,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, t-butyl peroxy isopropyl carbonate, t-butyl perisononaoate, 2,5-dimethylhexane 2,5-dibenzoate, t-butyl peracetate, t-amyl perbenzoate, t-butyl perbenzoate, 2,2-bis (t-butylperoxy)butane, 2,2 bis (t-butylperoxy)propane, dicumyl peroxide, 2,5-dimethylhexane-2,5-di-t-butylperoxide, 3-t-butylperoxy 3-phenylphthalide, di-t-amyl peroxide, α,α′-bis(t-butylperoxy isopropyl)benzene, 3,5-bis(t-butylperoxy)3,5-dimethyl 1,2-dioxolane, di-t-butyl peroxide, 2,5-dimethylhexyne-2,5-di-t-butylperoxide, 3,3,6,6,9,9-hexamethyl 1,2,4,5-tetraoxa cyclononane, p-menthane hydroperoxide, pinane hydroperoxide, diisopropylbenzene mono-α-hydroperoxide, cumene hydroperoxide or t-butyl hydroperoxide.

Preferably the radical source, generating the free radical initiator is present in an amount of from 0.01 mol % to 30 mol %.

Preferably when G₁₁ is —O· the molar ratio of the free radical source to the compound of formula I is from 1:2 to 20:1, more preferably from 1:1 to 5:1.

Preferably the ethylenically unsaturated monomer or oligomer is selected from the group consisting of alkene, styrene, substituted styrene, conjugated dienes, acrolein, vinyl acetate, (alkyl)acrylic acidanhydrides, (alkyl)acrylic acid salts, (alkyl)acrylic esters or (alkyl)acrylamides.

More preferably the ethylenically unsaturated monomer is ethylene, propylene, n-butylene, i-butylene, isoprene, 1,3-butadiene, α-C₅-C₁₈alkene, styrene, α-methyl styrene, p-methyl styrene or a compound of formula CH₂═C(R_(a))—(C═Z)—R_(b), wherein R_(a) is hydrogen or C₁-C₄alkyl, R_(b) is NH₂, O(Me), glycidyl, unsubstituted C₁-C₁₈alkoxy, C₁-C₁₈alkoxy interrupted by at least one N and/or O atom, or hydroxy-substituted C₁-C₁₈alkoxy, C₁-C₁₈alkoxy interrupted by at least one N and/or O atom, unsubstituted C₁-C₁₈alkylamino, di(C₁-C₁₈alkyl)amino, hydroxy-substituted C₁-C₁₈alkylamino or hydroxy-substituted di(C₁-C₁₈alkyl)amino, —O—CH₂—CH₂—N(CH₃)₂ or —O—CH₂—CH₂—N⁺H(CH₃)₂ An⁻;

An⁻ is a anion of a monovalent organic or inorganic acid;

Me is a monovalent metal atom

Z is oxygen or sulfur.

Particularly preferred are monomers, wherein R_(a) is hydrogen, R_(b) is NH₂, unsubstituted or with hydroxy substituted C₁-C₄alkoxy, unsubstituted C₁-C₄alkylamino, di(C₁-C₄alkyl)amino, hydroxy-substituted C₁-C₄alkylamino or hydroxy-substituted di(C₁-C₄alkyl)amino;and Z is oxygen.

Most preferably the ethylenically unsaturated monomer is styrene, α-methyl styrene or p-methyl styrene and ethylene.

To increase polymerization rate furthermore, organic sulfonic or organic carboxylic acids (U.S. Pat. No. 5,322,912), sulfonic acid salts(U.S. Pat. No. 5,608,023), acid anhydrides (Malmstrom, E.; Miller, R. D.; Hawker, C. J. Tetrahedron 1997, 53, 15225-15236) or vinyl monomers containing acid groups (WO 96/18663) can be added to the polymerization process. Furthermore, the polymerization rate can be enhanced by the addition of phosphorous compounds (U.S. Pat. No. 5,610,249), electron accepting compounds (EP 0 773 232), dimethylsulfoxide (U.S. Pat. No. 5,412,012), reducing agents (EP 0 897 930) or metal catalysts and stable free radical complex catalysts (U.S. Pat. No. 5,744,560).

Another subject of the present invention is a process for preparing an oligomer, a cooligomer, a polymer or a copolymer (block or random) by free radical polymerization of at least one ethylenically unsaturated monomer or oligomer, which comprises (co)polymerizing the monomer or monomers/oligomers in the presence of a compound of formula (I) as described above, wherein if

G₁₁ is —O—X

a) under reaction conditions capable of effecting scission of the O—X bond to form two free radicals, the radical •X being capable of initiating polymerization; or if

G₁₁ is O•

b) additionally in the presence of a free radical source, liberating a free radical which is capable of initiating polymerization.

Preferred is a process, wherein the scission of the O—X bond is effected by ultrasonic treatment, heating or exposure to electromagnetic radiation, ranging from γ to microwaves. More preferred is a process, wherein the scission of the O—X bond is effected by heating and takes place at a temperature of between 50° C and 180° C.

Preferred is a process, wherein the polymerization takes place at a temperature between 50° and 180° C., more preferred at a temperature between 110° and 150° C.

A further subject of the invention is a process for preparing an oligomer, a cooligomer, a polymer or a copolymer (block or random) by free radical polymerization of at least one ethylenically unsaturated monomer or oligomer, which comprises (co)polymerizing the monomer or monomers/oligomers in the presence of

a) a compound having at least two

 groups, under reaction conditions capable of effecting scission of the O—X bond to form two free radicals, the radicals •X being capable of initiating polymerization and the radicals

 being stable free nitroxyl radicals or

b) an initiator/regulator compound having at least two stable free nitroxyl radicals

 and additionally a free radical source is present; and

wherein after polymerization is completed at least one additional heating step at a temperature from 140° to 280° C. is applied.

Examples of suitable compounds are those of Formula (I) and the compounds given below.

Nitroxyl-ethers having at least two

groups and nitroxyl radicals having at least two stable nitroxyl groups

suitable for the above process are for example compounds of the formula (II)

 in which n₁ is a number from 2 to 4, G and G₁, independently of one another, are hydrogen or methyl,

G₁₁ is O• or O—X

G₁₂, if n₁ is 2, is C₂-C₁₂alkylene, C₄-C₁₂alkenylene, xylylene, a divalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid, dicarbamic acid or phosphorus-containing acid or a divalent silyl radical, preferably a radical of an aliphatic dicarboxylic acid having 2 to 36 carbon atoms, or a cycloaliphatic or aromatic dicarboxylic acid having 8-14 carbon atoms or of an aliphatic, cycloaliphatic or aromatic dicarbamic acid having 8-14 carbon atoms, where each dicarboxylic acid may be substituted in the aliphatic, cycloaliphatic or aromatic moiety by one or two —COOZ₁₂ groups,

G₁₂, if n₁ is 3, is a trivalent radical of an aliphatic, cycloaliphatic or aromatic tricarboxylic acid, which may be substituted in the aliphatic, cycloaliphatic or aromatic moiety by —COOZ₁₂, of an aromatic tricarbamic acid or of a phosphorus-containing acid, or is a trivalent silyl radical,

and G₁₂, if n₁ is 4, is a tetravalent radical of an aliphatic, cycloaliphatic or aromatic tetracarboxylic acid.

Alkyl with up to 20 carbon atoms is, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

Examples of several G₁₂ radicals are given below.

If G₁₂ is a divalent radical of a dicarboxylic acid, it is, for example, a malonyl, succinyl, glutaryl, adipoyl, suberoyl, sebacoyl, maleoyl, itaconyl, phthaloyl, dibutylmalonyl, dibenzylmalonyl, butyl(3,5-di-tert-butyl-4-hydroxybenzyl)malonyl or bicycloheptenedicarbonyl radical or a group of the formula

If G₁₂ is a trivalent radical of a tricarboxylic acid, it is, for example, a trimellitoyl, citryl or nitrilotriacetyl radical.

If G₁₂ is a tetravalent radical of a tetracarboxylic acid, it is, for example, the tetravalent radical of butane-1,2,3,4-tetracarboxylic acid or of pyromellitic acid.

If G₁₂ is a divalent radical of a dicarbamic acid, it is, for example, hexamethylenedicarbamoyl or 2,4-toluylenedicarbamoyl radical.

Preference is given to compounds of the formula (II) in which G and G₁ are hydrogen, G₁₁ O· n₁ is 2 and G₁₂ is the diacyl radical of an aliphatic dicarboxylic acid having 4-12 carbon atoms.

A typical example is di(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)sebacate. These compounds are in principal known and partially commercially available.

Further suitable examples of nitroxyl-ethers and nitroxyl radicals are described in GB 2335190

Preferably the initiator/regulator compound useful in the above process is of formula (I) including the preferences as described above.

The additional heating step may be performed directly in the polymerization apparatus or the polymer may be first isolated cooled down to room temperature stored for a while and then heated again to a temperature between 140° C. and 280° C., more preferably between 140° C. to 200° C. and most preferably between 150° C. to 180° C.

The heating step may be applied from 10 seconds to 2 hours, preferably from 1 minute to 60 minutes and more preferably from 1 minute to 30 minutes.

In a preferred embodiment of the invention the polymer is isolated with conventional techniques. The isolating step of the present process may be carried out by known procedures, e.g. by precipitation, distilling and filtering off unreacted monomer. After completing the reaction the polymer may be filtered off, followed by evaporation of the solvent or by precipitation of the polymer in a suitable liquid phase, filtering the precipitated polymer, washing and drying.

The above described additional heating step is then applied to the dried polymer.

The heating step may be performed in every suitable vessel. It is also possible to heat the polymer in an extruder, mixer or kneading apparatus.

The advantage of the heating step lies in the formation of a more uniform polymer as is proven by the reduced molecular weight distribution after thermal exposure compared to the original material.

During the additional heating step conventional polymer additives such as antioxidants or phosphorous compounds may be added. Examples are given below.

1. Antioxidants

1.1. Alkylated monophenols, for example 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-di-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(α-methylcyclohexyl)-4,6-dimethyphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1′-methylundec-1′-yl)phenol, 2,4-dimethyl-6-(1′-methylheptadec-1′-yl)phenol, 2,4-dimethyl-6-(1′-methyltridec-1′-yl)phenol and mixtures thereof.

1.2. Alkylthiomethylphenols, for example 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4-nonylphenol.

1.3. Hydroquinones and alkylated hydroquinones, for example 2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, bis-(3,5-di-tert-butyl-4-hydroxyphenyl)adipate.

1.4. Tocopherols, for example α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol and mixtures thereof (Vitamin E).

1.5. Hydroxylated thiodiphenyl ethers, for example 2,2′-thiobis(6-tert-butyl-4-methylphenol), 2,2′-thiobis(4-octylphenol), 4,4′-thiobis(6-tert-butyl-3-methylphenol), 4,4′-thiobis(6-tert-butyl-2-methylphenol), 4,4′-thiobis-(3,6-di-sec-amylphenol), 4,4′-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide.

1.6. Alkylidenebisphenols, for example 2,2′-methylenebis(6-tert-butyl-4-methylphenol), 2,2′-methylenebis(6-tert-butyl-4-ethylphenol), 2,2′-methylenebis[4-methyl-6-(α-methylcyclohexyl)phenol], 2,2′-methylenebis(4-methyl-6-cyclohexylphenol), 2,2′-methylenebis(6-nonyl-4-methylphenol), 2,2′-methylenebis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2′-methylenebis[6-(α-methylbenzyl)-4-nonylphenol], 2,2′-methylenebis[6-(α,α-dimethylbenzyl)-4-nonylphenol], 4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis[3,3-bis(3′-tert-butyl-4′-hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene, bis[2-(3′-tert-butyl-2′-hydroxy-5′-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane, 2,2-bis-(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis-(5-tert-butyl-4-hydroxy2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.

1.7. O-, N- and S-benzyl compounds, for example 3,5,3′,5′-tetra-tert-butyl-4,4′-dihydroxydibenzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, bis(3,5-di-tert-butyl-4-hydroxybenzyl)sulfide, isooctyl-3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate.

1.8. Hydroxybenzylated malonates, for example dioctadecyl-2,2-bis-(3,5-di-tert-butyl-2-hydroxybenzyl)-malonate, di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malonate, di-dodecylmercaptoethyl-2,2-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.

1.9. Aromatic hydroxybenzyl compounds, for example 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

1.10. Triazine Compounds, for example 2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hexahydro-1,3,5-triazine, 1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.

1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

1.12. Acylaminophenols, for example 4-hydroxylauranilide, 4-hydroxystearanilide, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate.

1.13. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.14. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.15. Esters of β-(3,5-dicyclohexal-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

1.17. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid e.g. N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide, N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamide, N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazide, N,N′-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide (Naugard®XL-1 supplied by Uniroyal).

2. Phosphites and phosphonites, for example triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)-pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tris(tert-butylphenyl)pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl) 4,4′-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenz[d,g]-1,3,2-dioxaphosphocin, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenz[d,g]-1,3,2-dioxaphosphocin, bis(2,4-di-tert-butyl-6-methylphenyl)methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite, 2,2′,2″-nitrilo[triethyltris(3,3′,5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite], 2-ethylhexyl(3,3′,5,5′-tetra-tert-butyl-1,1′-biphenyl-2,2′-diyl)phosphite.

Especially preferred are the following phosphites:

Tris(2,4-di-tert-butylphenyl)phosphite (Irgafos®168, Ciba-Geigy), tris(nonylphenyl)phosphite,

In addition to the initiators/regulators of the present invention there may be other compounds present during polymerization having a monofunctional N—O· moiety.

Suitable compounds are for example described in EP-A-621 878, WO 96/24620, U.S. Pat. No. 4,581,429, U.S. Pat. No. 5,721,320, U.S. Pat. No. 5,627,248, WO 98/13392, WO98/30601 or in WO 98/44008

Preferred is a compound of formula (X)

wherein R₁₀₁ is H, —OH, —O—C₁-C₁₈alkyl.

The compounds of formula (X) are preferably present in an amount of from 0.1% to 30% by weight based on the monomer or monomer mixture. They may replace the amount of compounds of formula (I) of from 1% to 50%.

The process may be carried out in the presence of an organic solvent or in the presence of water or in mixtures of organic solvents and water. Additional cosolvents or surfactants, such as glycols or ammonium salts of fatty acids, may be present. Other suitable cosolvents are described hereinafter.

Preferred processes use as little solvents as possible. In the reaction mixture it is preferred to use more than 30% by weight of monomer and initiator, particularly preferably more than 50% and most preferrably more than 80%. In many cases it is possible to polymerize without any solvent.

If organic solvents are used, suitable solvents or mixtures of solvents are typically pure alkanes (hexane, heptane, octane, isooctane), aromatic hydrocarbons (benzene, toluene, xylene), halogenated hydrocarbons (chlorobenzene), ethylene glycol, ethylene glycol monomethyl ether), esters (ethyl acetate, propyl, butyl or hexyl acetate) and ethers (diethyl ether, dibutyl ether, ethylene glycol dimethyl ether), or mixtures thereof.

The aqueous polymerization reactions can be supplemented with a water-miscible or hydrophilic cosolvent to help ensure that the reaction mixture remains a homogeneous single phase throughout the monomer conversion. Any water-soluble or water-miscible cosolvent may be used, as long as the aqueous solvent medium is effective in providing a solvent system which prevents precipitation or phase separation of the reactants or polymer products until after all polymerization reactions have been completed. Exemplary cosolvents useful in the present invention may be selected from the group consisting of aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkyl pyrrolidinones, N-alkyl pyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxylic acids and salts thereof, esters, organosulfides, sulfoxides, sulfones, alcohol derivatives, hydroxyether derivatives such as butyl carbitol or cellosolve, amino alcohols, ketones, and the like, as well as derivatives thereof and mixtures thereof. Specific examples include methanol, ethanol, propanol, dioxane, ethylene glycol, propylene glycol, diethylene glycol, glycerol, dipropylene glycol, tetrahydrofuran, and other water-soluble or water-miscible materials, and mixtures thereof. When mixtures of water and water-soluble or water-miscible organic liquids are selected as the aqueous reaction media, the water to cosolvent weight ratio is typically in the range of about 100:0 to about 10:90.

The process is particularly useful for the preparation of block copolymers.

Block copolymers are, for example, block copolymers of polystyrene and polyacrylate (e.g., poly(styrene-co-acrylate) or poly(styrene-co-acrylate-co-styrene). They are useful as adhesives or as compatibilizers for polymer blends or as polymer toughening agents.

Furthermore, block copolymers of this invention, wherein the blocks alternate between polar monomers and non-polar monomers, are useful in many applications as amphiphilic surfactants or dispersants for preparing highly uniform polymer blends.

The (co)polymers of the present invention may have a number average molecular weight from 1000 to 1000,000 g/mol, preferably from 2000 to 250,000 g/mol and, more preferably, from 2000 to 200,000 g/mol. The number average molecular weight may be determined by size exclusion chromatography (SEC), matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) or, if the initiator carries a group which can be easily distinguished from the monomer(s), by NMR spectroscopy or other conventional methods.

The polymers or copolymers of the present invention have preferably a polydispersity of from 1.1 to 2, more preferably of from 1.2 to 1.8. Particularly when an additional heating step is applied, the polydispersity is preferably between 1.2 and 1.8.

The present invention also encompasses the synthesis of block, multi-block, star, gradient, random, hyperbranched and dendritic copolymers, as well as graft copolymers.

The polymers prepared by the present invention are useful for following applications:

adhesives, detergents, dispersants, emulsifiers, surfactants, defoamers, adhesion promoters, corrosion inhibitors, viscosity improvers, lubricants, rheology modifiers, thickeners, crosslinkers, paper treatment, water treatment, electronic materials, paints, coatings, photography, ink materials, imaging materials, superabsorbants, cosmetics, hair products, preservatives, biocide materials or modifiers for asphalt, leather, textiles, ceramics and wood.

Because the present polymerizaton is a “living” polymerization, it can be started and stopped practically at will. Furthermore, the polymer product retains the functional alkoxyamine group allowing a continuation of the polymerization in a living matter. Thus, in one embodiment of this invention, once the first monomer is consumed in the initial polymerizing step a second monomer can then be added to form a second block on the growing polymer chain in a second polymerization step. Therefore it is possible to carry out additional polymerizations with the same or different monomer(s) to prepare multi-block copolymers.

Furthermore, since this is a radical polymerization, blocks can be prepared in essentially any order. One is not necessarily restricted to preparing block copolymers where the sequential polymerizing steps must flow from the least stabilized polymer intermediate to the most stabilized polymer intermediate, such as is the case in ionic polymerization. Thus it is possible to prepare a multi-block copolymer in which a polyacrylonitrile or a poly(meth)acrylate block is prepared first, then a styrene or diene block is attached thereto, and so on.

A plurality of specifically designed polymers and copolymers are accessible by the present invention, such as star and graft (co)polymers as described, inter alia, by C. J. Hawker in Angew. Chemie, 1995, 107, pages 1623-1627, dendrimers as described by K. Matyaszewski et al. in Macromolecules 1996, Vol 29, No. 12, pages 4167-4171, graft (co)polymers as described by C. J. Hawker et al. in Macromol. Chem. Phys. 198, 155-166(1997), random copolymers as described by C. J. Hawker in Macromolecules 1996, 29, 2686-2688, or diblock and triblock copolymers as described by N. A. Listigovers in Macromolecules 1996, 29, 8992-8993.

A further subject of the invention is a polymer or oligomer having attached at least one oxyamine group of formula (I), obtainable by the above described process.

Still another subject of the invention is the use of a compound of formula (I) for the polymerization of ethylenically unsaturated monomers or oligomers.

The following examples illustrate the invention.

GENERAL POLYMERIZATION PROCEDURE

In a dry, argon-purged Schlenk tube, the amounts of nitroxyl stable free radical and radical initator given Table 1 are dissolved in 50 ml freshly distilled styrene. The solution is degassed in three consecutive freeze-thaw-cycles and then purged with argon. The stirred mixture/solution is then immersed in an oil bath and polymerized at 130° C. for 6 hours. After polymerization, residual monomer is removed under vacuum at 60° C. and the polymer is dried at 70° C. in vacuo until constant weight is achieved.

Control polymerizations without a stable free radical were carried out identically, at 80° C. Molecular weight and molecular weight distributions are determined by GPC on a HP 1090 liquid chromatograph (software: winGPC/Polymer Standard Services, Mainz, Germany) using THF as eluent and a column combination calibrated with narrow polystyrene standards (Polymer Laboratories).

Dibenzoyl peroxide (BPO) (Merck) was recrystallized from Methanol prior to use. Styrene was distilled under reduced pressure prior to use.

Nitroxyle (1):

prepared according to U.S. Pat. No. 5,216,156.

BPO is Dibenzoyl peroxide.

TABLE 1 Polymerization of styrene with compound 1, without additional heating step Conver- Example sion Conc. # (%) [mol/l] M_(n) M_(w) M_(w)/M_(n) control 98 [BPO] = 6.69 × 10⁻² 18200  49000 2.69 1A 73 [BPO] = 6.69 × 10⁻² 14400  25900 1.79 [101] = 2.9 × 10⁻² control 99 [BPO] = 6.69 × 10⁻³ 84000 180700 2.15 2A 77 [BPO] = 6.69 × 10⁻³ 73700 133700 1.81 [101] = 2.9 × 10⁻³ 3A 77 [BPO] = 6.69 × 10⁻³ 70300 132100 1.88 [1] = 2.9 × 10⁻³

TABLE 2 Polymerization of styrene with mixtures of nitroxide radicals Conver- Inventive sion Conc example % [mol/l] M_(n) M_(w) M_(w)/M_(n) 4A 59 [BPO] = 6.69 × 10⁻² 10500 15200 1.45 [1] = 1.45 × 10⁻² [2] = 4.35 × 10⁻² 5A 76 [BPO] = 6.69 × 10⁻³ 58500 94700 1.62 [1] = 1.45 × 10⁻³ [2] = 4.35 × 10⁻³

ratio of radical functionalities provided by each species: NO·(1):NO·(2)=1:1

TABLE 3 Polymerization of styrene with a mixture containing 60% tris-nitroxyl and 40% bis-nitroxyl radicals. Conver- Exp. Conc sion M_(n) M_(w)/ Nr. [mol/l] (%) (calc.) M_(n) M_(w) M_(n) #7A [BPO] = 6,69 × (64)  7850 16100 25000 1.56 10⁻² [NO ·] = 2,9 × 10⁻² #6A [BPO] = 6,69 × (77) 81200 78800 139900 1.77 10⁻³ [NO ·] = 2,9 × 10⁻³

Mixture of

TABLE 4 Polymerization with a mixture containing >90% tris nitroxyl and <10% bis nitroxyl radicals. Conver- Exp. Conc sion M_(n) M_(w)/ Nr. [mol/l] (%) (calc.) M_(n) M_(w) M_(n) #8 [BPO] = 6,69 × (58) 7100 14400  22100 1.54 10⁻² [NO ·] = 2,9 × 10⁻² #9A [BPO] = 6,69 × (84) 89300 74800 132800 1.77 10⁻³ [NO ·] = 2,9 × 10⁻³

The samples 1 A, 2A, 6A and 9A described above were subjected to an additional heating step of different time and temperature and M_(n) and M_(w) are measured thereafter.

TABLE 5 Results after applying additional heating steps of 60 min at 200° C. after polymerization M_(n) original M_(w) original M_(w)/M_(n) original material (A) material (A) material M_(n) 1st heat. (B) M_(w) 1st heat. M_(w)/M_(n) 1st heat. M_(n) 2nd heat (C) M_(w) 2nd heat M_(w)/m_(n) 2nd heat Example M_(n) 1st heat. (D) M_(w) 1st heat. M_(w)/M_(n) 1st heat. # (Antiox I added) (Antiox I added) (Antiox I added) 1A 14400 25900 1.79 1B 11500 14200 1.23 1C 10700 14000 1.22 1D 11200 13800 1.24 2A 73700 133700  1.81 2B 54200 79200 1.54 2C 52800 79200 1.54 2D 50600 75400 1.49

Antiox I is Irganox® 1076 supplied by Ciba Specialty Chemicals

TABLE 6 Additional heating step for 60 min at different temperatures M_(n) original M_(w) (A) M_(w)/M_(n (A)) material(A) original original M_(n) after heating at material(A) material(A) 180° C./60 min. (E) M_(w) (E) M_(w)/M_(n) (E) 200° C./60 min. (F) M_(w) (F) M_(w)/M_(n) (F) 220° C./60 min. (G) M_(w) (G) M_(w)/M_(n) (G) Example # 240° C./60 min. (H) M_(w) (H) M_(w)/M_(n) (H) 1A 14400 25900 1.79 1E 8800 13700 1.57 1F 10400 13500 1.31 1G 10300 13500 1.31 1H 10300 13300 1.29 2A 73700 133700  1.81 2E 51300 75700 1.48 2F 51600 74400 1.44 2G 48200 74500 1.54 2H 47100 72600 1.54

TABLE 7 Additional heating step of 60 min at different temperatures M_(n) original M_(w) (A) M_(w)/M_(n) (A) material(A) original original M_(n) after heating at material(A) material(A) 160° C./60 min. (B) M_(w) (B) M_(w)/M_(n) (B) 200° C./60 min. (C) M_(w) (C) M_(w)/M_(n) (C) Example # 240° C./60 min. (D) M_(w) (D) M_(w)/M_(n) (D) 6A 78800 139000 1.77 6B 64900 105600 1.63 6C 62700 103400 1.64 6D 57700  87000 1.51

TABLE 8 Additional heating step of 15 min at difterent temperatures M_(n) original M_(w) (A) M_(w)/M_(n) (A) material(A) original original M_(n) after heating at material(A) material(A) 160° C./15 min. (E) M_(w) (E) M_(w)/M_(n) (E) 200° C./15 min. (F) M_(w) (F) M_(w)/M_(n) (F) Example # 240° C./15 min. (G) M_(w) (G) M_(w)/M_(n) (G) 6A 78800 139000 1.77 6B 73400 127700 1.74 6C 61100 106300 1.74 6D 58900  96300 1.64

TABLE 9 Additional heating step for 5 min at different temperatures M_(n) original M_(w) (A) M_(w)/M_(n) (A) material(A) original original M_(n) after heating at material(A) material(A) 140° C./5 min. (B) M_(w) (B) M_(w)/M_(n) (B) 200° C./5 min. (C) M_(w) (C) M_(w)/M_(n) (C) 220° C./5 min. (D) M_(w) (D) M_(w)/M_(n) (D) Example # 240° C./5 min. (E) M_(w) (E) M_(w)/M_(n) (E) 9A 74800 132800 1.77 9B 73900 120900 1.64 9C 56500  90000 1.59 9D 52200  78600 1.51 9E 54200  75800 1.40 

What is claimed is:
 1. A polymerizable composition, comprising a) at least one ethylenically unsaturated monomer or oligomer, and b) a compound of formula (I)

 in which n is the number 1 or 2, and R₁ is a group of the formula

 in which G₁ and G₂ are hydrogen, methyl or, together, are a substituent ═O, E is —O— or —ND₃—, A is C₂-C₆alkylene or —(CH₂)₃—O— and x₁ is the number 0 or 1, D₃ is hydrogen, C₁-C₁₂alkyl, C₂-C₅hydroxyalkyl or C₅-C₇cycloalkyl, R₂ is identical to R₁ or is one of the groups —N(G₂₁)(G₂₂), —OG₂₃, —N(H)(CH₂OG₂₃) or —N(CH₂OG₂₃)₂, R₃, if n=1, is identical to R₁ and, if n=2, is an —E—D₄—E— group, in which D₄ is C₂-C₈alkylene or C₂-C₈alkylene which is interrupted by 1 or 2 —NG₂₁— groups, G₂₁ is C₁-C₁₂alkyl, cyclohexyl, benzyl or C₁-C₄-hydroxyalkyl or a group of the formula

G₂₂ is C₁-C₁₂alkyl, cyclohexyl, benzyl or C₁-C₄hydroxyalkyl, and G₂₃ is hydrogen, C₁-C₁₂alkyl or phenyl, or G₂₁ and G₂₂ together are C₄-C₅alkylene or C₄-C₅oxaalkylene, for example —CH₂CH₂—O—CH₂CH₂—, or a group of the formula —CH₂CH₂—N(G₁₁)—CH₂CH₂—; and G₁₁ is O· or —O—X, wherein X represents a group selected from the group consisting of —CH(aryl)₂, —CH₂-aryl,

 —CH₂—CH₂-aryl,

 (C₅-C₆cycloalkyl)₂CCN, (C₁-C₁₂alkyl)₂CCN, —CH₂CH═CH₂, (C₁-C₁₂)alkyl-CR₃₀—C(O)—(C₁-C₁₂)alkyl, (C₁-C₁₂)alkyl-CR₃₀—C(O)—(C₆-C₁₀)aryl, (C₁-C₁₂)alkyl-CR₃₀—C(O)—(C₁-C₁₂)alkoxy, (C₁-C₁₂)alkyl-CR₃₀—C(O)-phenoxy, (C₁-C₁₂)alkyl-CR₃₀—C(O)—N-di(C₁-C₁₂)alkyl, (C₁-C₁₂)alkyl-CR₃₀—CO—NH(C₁-C₁₂)alkyl, (C₁-C₁₂)alkyl-CR₃₀—CO—NH₂, —CH₂CH═CH—CH₃, —CH₂—C(CH₃)═CH₂, —CH₂—CH═CH-phenyl,

 —O—C(O)—C₁-C₁₂alkyl, —O—C(O)—(C₆-C₁₀)aryl, (C₁-C₁₂)alkyl-CR₃₀—CN,

 wherein R₃₀ is hydrogen or C₁-C₁₂alkyl; the aryl groups are unsubstituted or substituted with C₁-C₁₂alkyl, halogen, C₁-C₁₂alkoxy, C₁-C₁₂alkylcarbonyl, glycidyloxy, OH, —COOH or —COOC₁-C₁₂alkyl such that the free radical X· derived from X is an initiator of polymerization of ethylenically unsaturated monomers at a temperature of between 50° C. and 180° C.; and if G₁₁ is O·, a source of free radicals is additionally present.
 2. A composition according to claim 1, wherein in formula (I) X is selected from the group consisting of —CH₂-phenyl, CH₃CH-phenyl, (CH₃)₂C-phenyl, (CH₃)₂CCN, —CH₂CH═CH₂, CH₃CH—CH═CH₂ and O—C(O)-phenyl.
 3. A composition according to claim 1, wherein in formula (I) n is 1; R₁ and R₃ are a group of formula

R₂ is identical to R₁ and R₃, or is a group —N(G₂₁)(G₂₂), wherein x₁ is 0; G₁ is hydrogen; G₁₁ is O·; E is —ND₃; D₃ is C₁-C₁₂alkyl and G₂₁ and G₂₂ are independently C₁-C₁₂alkyl.
 4. A composition according to claim 1, wherein the ethylenically unsaturated monomer or oligomer is selected from the group consisting of alkene, styrene, substituted styrene, conjugated dienes, acrolein, vinyl acetate, (alkyl)acrylic acid anhydrides, (alkyl)acrylic acid salts, (alkyl)acrylic esters and (alkyl)acrylamides.
 5. A composition according to claim 3 wherein the ethylenically unsaturated monomer is ethylene, propylene, n-butylene, i-butylene, isoprene, 1,3-butadiene, α-C₅-C₁₈alkene, styrene, α-methyl styrene, p-methyl styrene or a compound of formula CH₂═C(R_(a))—(C═Z)—R_(b), wherein R_(a) is hydrogen or C₁-C₄alkyl, R_(b) is NH₂, O⁻(Me⁺), glycidyl, unsubstituted C₁-C₁₈alkoxy, C₁-C₁₈alkoxy interrupted by at least one N and/or O atom, or hydroxy-substituted C₁-C₁₈alkoxy, C₁-C₁₈alkoxy interrupted by at least one N and/or O atom, unsubstituted C₁-C₁₈alkylamino, di(C₁-C₁₈alkyl)amino, hydroxy-substituted C₁-C₁₈alkylamino or hydroxy-substituted di(C₁-C₁₈alkyl)amino, —O—CH₂—CH₂—N(CH₃)₂ or —O—CH₂—CH₂—N⁺H(CH₃)₂ An⁻; An⁻ is an anion of a monovalent organic or inorganic acid; Me is a monovalent metal atom; and Z is oxygen or sulfur.
 6. A composition according to claim 5, wherein R_(a) is hydrogen, R_(b) is NH₂, unsubstituted or hydroxy-substituted C₁-C₄alkoxy, unsubstituted C₁-C₄alkylamino, di(C₁-C₄alkyl)amino, hydroxy-substituted C₁-C₄alkylamino or hydroxy-substituted di(C₁-C₄alkyl)amino; and Z is oxygen.
 7. A composition according to claim 6, wherein the ethylenically unsaturated monomer is styrene, α-methyl styrene, p-methyl styrene or ethylene.
 8. A composition according to claim 1, wherein the compound of formula (I) is present in an amount of from 0.01 mol-% to 30 mol-%, based on the monomer or monomer mixture.
 9. A composition according to claim 1, wherein the source of a free radical initiator is a bis-azo compound, a peroxide or a hydroperoxide.
 10. A composition according to claim 1, wherein the radical source, generating the free radical initiator is present in an amount of 0.01 mol % to 30 mol %.
 11. A composition according to claim 1, wherein in formula (I); when G₁₁ is —O·, a molar ratio of the free radical source to the compound of formulae I is from 1:2 to 20:1. 